Torque transmission mechanism

This torque transmission mechanism (A) for an internal combustion engine, adapted to transmit a starting torque from a starter motor to a crankshaft (4) of the internal combustion engine, comprises a ring gear (2) that transmits the starting torque and a one-way clutch (8) disposed between the ring gear (2) and the crankshaft (4), said ring gear (2) comprising a gear side portion (20) to which the starting torque is transmitted from the starter motor via gear mesh and a flange (22) joining the gear side portion (20) to an inner ring (7) of the one-way clutch (8). The flange (22) is directly assembled to the inner ring (7) of the one-way clutch (8).